Gary Grubb targeted his two female victims while they were walking home from a nightclub in June 2009, Teesside Crown Court heard.
The 33-year-old then fled to his native Zimbabwe and was not arrested until August of this year.
Grubb, of Lamberhurst Grove, Kentshill, Milton Keynes, admitted four counts of sexual assault in Laycock Park.
Sergeant Simon Hurwood, of Cleveland Police, welcomed the sentence and praised Grubb’s victims for their strength.
He said: "Gary Grubb is clearly a dangerous individual.
"He followed the two female victims and waited until he was at a quiet location where he subjected them to a sickening sexual assault."
‘Courage and strength’
Sgt Hurwood said Grubb left the country and only returned when he realised he was about to be extradited.
He added: "My team and I were determined to do everything in our power to ensure he was returned to the UK and brought to justice.
"I would like to thank and commend both victims who have shown both strength and courage throughout this investigation and also their families who have been a tower of strength to them.
"Incidents of this nature are always extremely difficult for victims to deal and I hope the sentence goes a little way to help them re-build their lives."